National Transport Safety Board (NTSB) officials in the US have announced that the door plug from the Alaska Airlines Boeing 737 MAX 9 that suffered a decompression after departure from Portland International Airport (PDX) has been found in an Oregon backyard.
Finding the door plug could offer up vital clues as to the cause of the incident, which Boeing, Alaska Airlines, and other 737 MAX 9 operators will be hoping was an isolated event limited to the specific aircraft involved, rather than a fleetwide issue.
During a press conference held late on January 7, 2024, representatives from the NTSB disclosed that the missing part had been recovered from a residential backyard in Oregon, although the exact location was not disclosed.
“I’m excited to announce that we found the door plug,” said Jennifer Homendy, NTSB Chairperson. She added that the Oregon resident who had found the missing part had sent photos directly to the NTSB and Homendy thanked the individual for his efforts.
“We’re going to go pick that up and make sure that we begin analyzing it,” Homendy added, stating that two mobile phones had also been recovered in the vicinity – one in a different backyard and another at the side of a road.
Although this news will be welcomed by the wider airline industry, Homendy stated that some issues would hamper the probe into the incident. The most important of these is that the aircraft’s cockpit voice recorder’s recording of the event had been inadvertently recorded over and had not captured vital dialogue between the flight crew.
Currently, cockpit voice recorders only record two hours of dialogue on a loop before it is recorded over. The device onboard flight 1282 automatically recorded over the voice data pertinent to the incident because the unit was not powered down after landing back at Portland, according to Homendy.
“That is unfortunately a loss for us,” Homendy said. “That information is key, not just for our investigation, but for improving aviation safety.”
NTSB officials went on to comment on the examinations that will take place now that they are in possession of the door plug. Investigators will examine how the door plug (a panel where an optional emergency exit can be placed depending on passenger capacity) was fixed in place before it exited the aircraft.
Homendy said investigators were focusing their investigations on how the door plug was fastened to the fuselage and whether there were failures related to it. She added that despite the loss of the door plug, the structural integrity of the aircraft remained intact following the decompression event.
Homendy described two hinges at the bottom of the plug that allow a small degree of opening for routine inspections as well as four circular-shaped stop fittings.
“The purpose is to prevent that door plug from being pushed out of the airframe,” she said. “All those elements will get a close look.”
Restricted flight operations
Of crucial importance to the NTSB’s work will be several air pressurization alerts that went off on the plane during flights on December 7, 2023, and on January 3 and January 4, 2024, these being the two days leading up to the event on January 5, 2024.
Homendy said that Alaska Airlines had prohibited the aircraft from embarking on long flights over water (specifically operating flights to and from Hawaii) until the issue could be checked out more thoroughly. By the time the aircraft departed on flight 1282, heading from Portland to Ontario, California, that inspection had not been completed, Homendy said.
She said the issue had been described to the NTSB as “benign” and that it was unclear whether there was any correlation between those alerts and the incident itself.
Communication issues
Homendy went on to describe the communication issues on board the Boeing 737 as the pilots reported “a loud noise” and the cabin rapidly depressurized as the aircraft climbed out of Portland.
Additionally, the plane’s first officer lost her headset during the depressurization, and the captain also had headset problems. Hence, the crew resorted to turning on the cockpit speaker for communication, Homendy said.
At the same time, the cockpit door opened violently, and a laminated quick reference checklist used in emergencies flew out. The pilots turned to another quick reference guide, as a flight attendant took three attempts to close the cockpit door.
“The actions of the flight crew were really incredible,” Homendy said. “It was very violent when the door was expelled out of the plane. “There was a lot going on.”
The Federal Aviation Administration (FAA) has ordered certain Boeing 737 MAX 9s to be grounded pending an inspection and has issued a directive requiring inspections before certain aircraft can fly again.
The 737 MAX 9 involved in the incident (registered N704AL) had only been in service with Alaska Airlines for less than three months at the time of the incident. The aircraft was delivered to the carrier on October 31, 2023, and entered commercial service on November 11, 2023